<正>通过13C-NMR解析了采用传统工艺（碱-酸-碱工艺）合成聚乙烯醇改性脲醛树脂反应过程中的结构变化。并推测其反应。结果表明：碱性条件下，甲醛与尿素以加成反应为主，反应生成大量的-羟甲腺，尿素全部参与反应，甲醛此时以聚合状态存在，同时也有缩聚反应的发生；酸性阶段以缩聚反应为主，形成以亚甲基键或醚键连接大分子体系。聚合状态的甲醛已全部分解，并以甲二醇的形式参与缩聚反应；第3次尿素的加入明显地降低了反应体系中的游离甲醛分量，同时生成物主要为一羟甲脲。聚乙烯醇单体的化学结构在C-NMR上有较好的表征。但可以证明有聚乙烯醇缩甲醛生成的化学位移未被检测到，因此在该实验范围内，没有聚乙烯醇缩甲醛生成。

The olfactory responses of two termite species to several substances in different concentrations were studied by using the Y--tube olfactometer and EAG, The results showed that Coptotermes formosa*ms Shiraki was signicantly attracted by 0.1 μ L/mL Citral, 10 μ g/mL Vanillic acid and agaric powder. 10 μ L/mL Citral was deterrented to C. forrnosanus Shiraki. C. curvignathus Holrngren was signicantly attracted by 1 μ L/mL Citral and agaric powder. Citral, Vanillic acid, sugarcane powder, the dust of pine and agaric powder all elicited electroantennal responses in EAG test. EAG values became greater as the concentration increased. The EAG values of two termites treated by citral were all higher than vanillic acid. The results showed that those components can be used in termites traps.